1. Field of the Invention
This invention relates to chemical compounds of the peptide type produced by synthetic methods and includes various processes.
2. Description of the Prior Art
Umezawa et al. have previously succeeded in isolating Bestatin [(2S, 3R)-3-amino-2-hydroxy-4-phenylbutanoyl-(S)-leucine] having a strong inhibitory activity against aminopeptidase B, leucine aminopeptidase and Bleomycin hydrolase from the culture of Bestatin-producing fungus belonging to the actinomyces. See, for example, U.S. Pat. No. 4,029,547 and J. Antibiotics, 29, 97-103 and 600-601 (1976).
Taking note of the excellent physiological activities of Bestatin, the present inventors have made researches into the method for synthetic preparation of this compound and novel peptides having similar structure to Bestatin and considered to possess the same physiological activities as Bestatin, and succeeded to synthesize Bestatin and its analogous compounds represented by the following general formula: ##STR3## wherein R.sub.1 is a lower alkyl group, cycloalkanoalkyl group, phenyl group, benzyl group or substituted benzyl group, and R.sub.2 is an alkyl group having 1 to 6 carbon atoms, hydroxyalkyl group, mercaptoalkyl group, carboxyamidoalkyl group, alkoxyalkyl group, alkyl mercaptoalkyl group, carboxyalkyl group, aryl group, aralkyl group or substituted aralkyl group. See, for example, U.K. Pat. No. 1,510,477 and J. Medicinal Chemistry 20(4), 510-515 (1977).